The basic structure of rolling bearings

The working principle of rolling bearings is to replace sliding friction with rolling friction, and their structure is generally a mechanical basic component composed of two rings, a set of rolling elements, and a cage. Due to different working conditions of rolling bearings, there are different requirements for the structure, load capacity, and performance of the bearings. Therefore, rolling bearings also have various structures. However, the most basic structure of rolling bearings is composed of an inner ring, an outer ring, rolling elements, and a cage.

The functions of each structural component of the bearing:

The inner ring of a radial bearing is usually tightly fitted with the shaft and runs together with the shaft, while the outer ring forms a transitional fit with the bearing seat or mechanical housing hole to provide support. In some cases, radial bearings also have an outer ring running, with the inner ring fixed to provide support or both the inner and outer rings running simultaneously. The thrust bearing is called a shaft ring that fits tightly with the shaft and moves together, and the seat ring that forms a transitional fit with the bearing seat or mechanical housing hole and plays a supporting role. Rolling elements (steel balls, rollers, or needle rollers) are usually uniformly arranged between two rings in a bearing through a cage for rolling motion. Their shape, size, and quantity directly affect the load capacity and performance of the bearing. In addition to evenly separating the rolling elements, the cage can also guide the rotation of the rolling elements and improve the internal lubrication performance of the bearing.

Classification of rolling bearings

1. Classify by rolling bearing structure type

(1) Bearings are divided into:

Centripetal bearings - rolling bearings mainly used to withstand radial loads, with nominal contact angles ranging from 0 to 45. According to different nominal contact angles, it can be divided into radial contact bearings - radial contact bearings with a nominal contact angle of 0, and radial contact bearings - radial contact bearings with a nominal contact angle greater than 0 to 45.

Thrust bearings - rolling bearings mainly used to withstand axial loads, with a nominal contact angle greater than 45 to 90. According to different nominal contact angles, it can be divided into axial contact bearings - thrust bearings with a nominal contact angle of 90: thrust angle contact bearings - thrust bearings with a nominal contact angle greater than 45 but less than 90.

(2) Bearings are divided into:

Ball bearings - rolling elements are balls:

Roller bearings - The rolling elements are rollers. Roller bearings are divided into cylindrical roller bearings according to the type of roller - the rolling element is a cylindrical roller bearing, and the length to diameter ratio of the cylindrical roller is less than or equal to 3; Needle roller bearing - The rolling element is a needle roller bearing, where the length to diameter ratio of the needle roller is greater than 3, but the diameter is less than or equal to 5mm; Conical roller bearings - rolling elements are bearings with conical rollers; Spherical roller bearings are bearings with spherical rolling elements.

(3) Bearings can be divided into:

Self aligning bearings - bearings with spherical raceways that can adapt to angular deviations and angular movements between the axis lines of two raceways;

Non self-aligning bearings (rigid bearings) - bearings that can resist axial deviation between raceways.

(4) Bearings are divided into:

Single row bearing - a bearing with one row of rolling elements;

Double row bearings - bearings with two rows of rolling elements;

Multi row bearings - bearings with more than two rows of rolling elements, such as three row and four row bearings.

(5) Bearings are divided into:

Separable bearings - bearings with separable components;

Non separable bearings - bearings in which the rings cannot be freely separated after final assembly.

(6) Bearings can be classified into various structural types based on their structural shape, such as the presence or absence of loading slots, the presence or absence of inner and outer rings and rings, the structure of the retaining edge, and even the presence or absence of a cage.

2. According to the size of rolling bearings, bearings are classified into:

(1) Micro bearings - bearings with a nominal outer diameter range of 26mm or less;

(2) Small bearings - bearings with a nominal outer diameter range of 28-55mm;

(3) Small and medium-sized bearings - bearings with a nominal outer diameter range of 60-115mm;

(4) Medium and large-sized bearings - bearings with a nominal outer diameter range of 120-190mm

(5) Large bearings - bearings with a nominal outer diameter range of 200-430mm;

(6) Extra large bearings - bearings with a nominal outer diameter range of 440mm or more.